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TORONTO – Ontario’s political leaders appear to be summoning their federal reserves to help fight the June 12 election campaign.

Premier Kathleen Wynne brought in former Liberal prime minister Paul Martin on Thursday to help plug her proposed provincial pension plan – a cornerstone of her campaign and a big bone of contention between her and the Harper Conservatives.

Martin, who was recruited by Wynne to help with the made-in-Ontario plan, joined her in castigating the federal Tories for not expanding the Canada Pension Plan.

The Ontario Tories have called Wynne’s pension idea a payroll tax, which shows a “complete ignorance of what pension plan investing is all about,” he said.

“This is not a tax, and anybody who says it is a tax is either trying to fool people or they just don’t understand what it’s all about,” said Martin, who as finance minister led reforms to the CPP in the 1990s.

“This is an investment in everybody’s future.”

Justin Trudeau is also expected to hop aboard federal Liberal train, joining Wynne and his candidate Adam Vaughan at a rally this afternoon in Trinity-Spadina, a coveted riding both the federal and provincial Liberals are hoping to steal from the New Democrats.

WATCH: Wynne defended her decision to pursue a provincial pension plan Friday, accusing the other provincial party leaders – as well as PM Stephen Harper – of not showing leadership on the issue of the rapidly aging population.

But the Liberal leader’s appearance at Wynne’s side won’t have been the only sighting of a federal politician on the campaign trail.

John Baird and Tony Clement campaign for Hudak

Several federal ministers have shown their support for Ontario PC Leader Tim Hudak, including Foreign Affairs Minister John Baird, Minister of State for Democratic Reform Pierre Pollievre and Treasury Board president Tony Clement.

The most visible is Baird, who introduced Hudak at a town hall event in Toronto earlier this week and attended his speech in Ottawa last week. He and Clement worked with Hudak in the Ontario legislature under the former Conservative government.

It’s not uncommon for federal party members to lend a hand to their provincial cousins in election campaigns.

NDP Leader Andrea Horwath is getting help from federal New Democrat volunteers and Baird’s aide Rick Roth is a member of the Hudak tour team.

But Clement has engaged in a war of words with Wynne, calling the proposed Ontario pension plan a “huge tax grab” and saying he wanted her to lose the election and hoped Hudak will be premier.

He slammed Wynne again this week in the Toronto Sun for badgering Ottawa over funding for a transportation route to the Ring of Fire development in northern Ontario.

Wynne hasn’t been shy about her feelings towards the federal Tories either, calling Prime Minister Stephen Harper’s antipathy towards pension reform “offensive and inexplicable” before the snap election was called and repeating her complaints during the campaign.